diff --git a/platform/core-api/src/com/intellij/openapi/application/AcceptNestedTransactions.java b/platform/core-api/src/com/intellij/openapi/application/AcceptNestedTransactions.java
new file mode 100644
index 000000000000..404a54897eaf
--- /dev/null
+++ b/platform/core-api/src/com/intellij/openapi/application/AcceptNestedTransactions.java
@@ -0,0 +1,38 @@
+/*
+ * Copyright 2000-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.openapi.application;
+
+import java.lang.annotation.*;
+
+/**
+ * Add this annotation to modal dialogs (DialogWrapper inheritors) shown from within transactions,
+ * to allow nested transactions inside those dialogs.
+ *
+ * @see TransactionGuard#acceptNestedTransactions(TransactionKind...)
+ * @since 146.*
+ * @author peter
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Inherited
+public @interface AcceptNestedTransactions {
+
+  /**
+   * @return the kinds of transaction to allow inside the dialog
+   */
+  TransactionKind.Common[] value();
+}
diff --git a/platform/core-api/src/com/intellij/openapi/application/TransactionGuard.java b/platform/core-api/src/com/intellij/openapi/application/TransactionGuard.java
index 890f9289420d..9134e9c58fbd 100644
--- a/platform/core-api/src/com/intellij/openapi/application/TransactionGuard.java
+++ b/platform/core-api/src/com/intellij/openapi/application/TransactionGuard.java
@@ -60,7 +60,10 @@ import org.jetbrains.annotations.NotNull;
  *
  * Having said all that, it's still advisable that the transactions be as short as possible and preferably exclude any modal dialogs
  * for which transaction-ness is not critical. So a better overall strategy would be to either make the dialogs non-modal,
- * or at least make them and the code that shows them prepared for possible model changes while the dialog is shown.
+ * or at least make them and the code that shows them prepared for possible model changes while the dialog is shown.<p/>
+ *
+ * Dialogs that have per-project modality must never be shown from a transaction, because this would disallow making changes in another
+ * project: they'd be blocked by the running transaction.
  *
  * Q: I've got <b>"Write access is allowed from model transactions only"</b> exception, what do I do?<br/>
  * A: Add a transaction somewhere into the call stack, to the outermost callee where having read/write model consistency is needed.
@@ -177,8 +180,10 @@ public abstract class TransactionGuard {
   /**
    * Allow incoming transactions of the specified kinds to be executed immediately, instead of being queued until the current transaction is finished.<p/>
    *
-   * Example: outer transaction has shown a dialog with an editor, and typing into that editor (which requires a transaction for changing document)
-   * should be allowed.
+   * Example: outer transaction has shown a dialog with an editor, and typing into that editor (which requires a transaction for changing document).
+   * should be allowed.<p/>
+   *
+   * For dialogs, consider using {@link AcceptNestedTransactions} annotation instead of explicit call to this method.
    * @param kinds kinds of transactions to allow
    * @return a token object for this session. Please call {@link AccessToken#finish()} (inside finally clause) when you don't want
    * nested transactions anymore.
diff --git a/platform/core-api/src/com/intellij/openapi/application/TransactionKind.java b/platform/core-api/src/com/intellij/openapi/application/TransactionKind.java
index 6a666b98b0ad..b4db511c2b63 100644
--- a/platform/core-api/src/com/intellij/openapi/application/TransactionKind.java
+++ b/platform/core-api/src/com/intellij/openapi/application/TransactionKind.java
@@ -18,8 +18,8 @@ package com.intellij.openapi.application;
 import com.intellij.openapi.editor.Document;
 
 /**
- * A kind of transaction used in {@link TransactionGuard#submitMergeableTransaction(TransactionKind, Runnable)}
- * and {@link TransactionGuard#acceptNestedTransactions(TransactionKind...)}.
+ * A kind of transaction used in {@link TransactionGuard#submitMergeableTransaction(TransactionKind, Runnable)},
+ * {@link TransactionGuard#acceptNestedTransactions(TransactionKind...)} and {@link AcceptNestedTransactions}.
  */
 public interface TransactionKind {
   /**
diff --git a/platform/platform-api/src/com/intellij/openapi/ui/DialogWrapper.java b/platform/platform-api/src/com/intellij/openapi/ui/DialogWrapper.java
index f66a87c3c9d0..b39ef3d91bb1 100644
--- a/platform/platform-api/src/com/intellij/openapi/ui/DialogWrapper.java
+++ b/platform/platform-api/src/com/intellij/openapi/ui/DialogWrapper.java
@@ -24,9 +24,7 @@ import com.intellij.openapi.Disposable;
 import com.intellij.openapi.MnemonicHelper;
 import com.intellij.openapi.actionSystem.*;
 import com.intellij.openapi.actionSystem.ex.ActionUtil;
-import com.intellij.openapi.application.ApplicationInfo;
-import com.intellij.openapi.application.ApplicationManager;
-import com.intellij.openapi.application.ModalityState;
+import com.intellij.openapi.application.*;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.help.HelpManager;
 import com.intellij.openapi.keymap.KeymapUtil;
@@ -1641,6 +1639,16 @@ public abstract class DialogWrapper {
 
   @NotNull
   private AsyncResult<Boolean> invokeShow() {
+    Window window = myPeer.getWindow();
+    if (window instanceof JDialog && ((JDialog)window).getModalityType() == Dialog.ModalityType.DOCUMENT_MODAL) {
+      if (ApplicationManager.getApplication().isWriteAccessAllowed()) {
+        LOG.error("Project-modal dialogs should not be shown under a write action.");
+      }
+      if (TransactionGuard.getInstance().isInsideTransaction()) {
+        LOG.error("Project-modal dialogs should not be shown inside a transaction. See TransactionGuard documentation.");
+      }
+    }
+
     final AsyncResult<Boolean> result = new AsyncResult<Boolean>();
 
     ensureEventDispatchThread();
@@ -1658,7 +1666,10 @@ public abstract class DialogWrapper {
       }
     });
 
-    myPeer.show();
+    AcceptNestedTransactions anno = getClass().getAnnotation(AcceptNestedTransactions.class);
+    try (AccessToken ignore = anno == null ? null : TransactionGuard.getInstance().acceptNestedTransactions((TransactionKind[])anno.value())) {
+      myPeer.show();
+    }
 
     return result;
   }